1. Field of the Invention
The invention relates to a lever-type connector and to a method for assembling such a connector.
2. Description of the Related Art
Lever-type connectors facilitate the mating of two connector housings, and are used in multi-contact connectors and other situations where a large connecting force is required. A known lever-type connector has male and female housings configured for mating with one another. A lever is mounted pivotally on the male housing and is formed with a cam groove. The female housing is formed with a follower configured for engagement in the cam groove at the beginning of the mating process. The cam groove has a side surface that pushes the follower as the lever is pivoted and moves the housings into a fully mated condition. A locking mechanism is provided between the lever and the mating housing to lock the housings in a fully mated condition.
The pivoting movement of the lever may be interrupted before the housings are connected properly. U.S. Pat. No. 5,562,465 shows a connector that attempts to avoid such a problem. This connector has a lever with an integral spring piece, and a mating housing with a striking portion disposed for engagement by the spring piece near the end of the pivotal movement of the lever. Thus, pivoting movement of the lever deforms the spring piece as the housings approach a fully connected condition. The locked engagement of two properly connected housings resists the resilient restoring forces of the spring piece. However, the restoring force of the spring piece pushes the lever back, if the housings are not locked together. In this way, partial connection of the housings is identified.
Connection can be detected satisfactorily in the prior art connector. However, the spring piece is left resiliently deformed after the housings are connected properly and locked together. Thus, the spring piece may experience a permanent set and may fatigue over time. As a result, the spring piece cannot be expected to display a connection detecting function when the two housings are reconnected after being separated for maintenance or other reason. Therefore, there has been a demand for a new means.
The present invention was developed in view of the above problem, and an object thereof is to allow two housings of a lever-type connector to be connected properly with high reliability.
The invention is directed to a lever-type connector with first and second housings that are connectable with each other. A lever is supported pivotally on the first housing and has at least one curved cam surface that gradually approaches the center of rotation of the lever. At least one follower is provided on the second housing and is engageable with the cam surface so that the housings are connected as the lever is pivoted. A resistance means is provided for giving a peak operation resistance to the lever when the lever is pivoted to a position immediately before the housings are connected properly.
A locking mechanism may be provided between the lever and the second housing to lock the housings together when the housings reach a properly connected state. The peak operation resistance preferably is larger than a resistance that acts when the housings are locked.
The housings are connected gradually as the lever is pivoted, and the operation resistance is peaked by the resistance means immediately before the housings are connected properly. The peak operation resistance is larger than the resistance that acts when the housings are locked. Thus, an inertial force pushes the second housing as the lever is pivoted to overcome the peak operation resistance. Consequently, the housings are connected properly and locked together with high reliability due to the inertial locking mechanism.
The resistance means preferably comprises a portion of the cam surface where a distance from the center of rotation decreases at a higher rate. More particularly, portions of the cam surface that contact the follower immediately before the housings are connected properly are inclined more steeply than other portions of the cam surface. Accordingly, the peak operation resistance is higher as the lever approaches the end of its pivotal movement. The peak operation resistance is obtained merely by changing the shape of the cam surface, and without providing a special resistance member. Thus, the resistance means is simple and inexpensive.
The resistance means preferably achieves the peak operation resistance when the housings have moved by a connection stroke larger than about 80%, preferably larger than 85%, and most preferably larger than 90% of a connection stroke needed to properly connect the housings. However, the resistance means preferably achieves the peak operation resistance when the housings have moved by a connection stroke less than 95% of a connection stroke needed to reach proper connection.
At least one starting position locking means may be provided on the lever, the first housing and/or the second housing to lock the lever temporarily in a starting position where the housings can be connected. Additionally, at least one releasing means may be provided for releasing the starting position locking means when the housings are to be mated so that the lever can pivot.
The invention also is directed to a method of assembling a lever-type connector. The method comprises partly mating first and second housings, and pivoting a lever on the first housing to connect the housings by the function of a cam means. An operation resistance of the lever is set to comprise a peak operation resistance when the lever is pivoted to a position immediately before the housings are connected properly connected.
The method may further comprise locking the two housings together with a locking mechanism when the housings reach a properly connected state.
Preferably, the peak operation resistance is larger than a resistance that acts when the housings are locked.
The method may comprise reaching a peak operation resistance when the housings have moved by a connection stroke larger than about 80%, preferably larger than 85% and most preferably larger than 90% of a connection stroke that properly connects the housings. However, the connection stroke for peak operation resistance preferably is less than 95% of a connection stroke needed to connect the housings properly.